Wireless telecommunications networks are known. Base stations in such networks provide wireless connectivity to user equipment within a geographical area or cell, associated with the base station. The wireless communication links between the base station and each of the user equipment typically include one or more downlink (or forward) channels for transmitting information from the base station to the user equipment and one or more uplink (or reverse) channels for transmitting information from the user equipment to the base station.
Multiple-input-multiple-output (MIMO) techniques may be employed when the base station and, optionally, the user equipment include multiple antennas. For example, user equipment that includes multiple antennas can transmit multiple independent and distinct signals to base stations on the same a frequency, using the same code and within the same transmission time interval (TTI) which can be resolved by the base stations. For example, individual user equipment is able to transmit two streams of Enhanced Data Channel (E-DCH) in the uplink using the same uplink resource (frequency, time and code) which means that the user equipment is capable of performing a rank two transmission (as opposed to a rank one transmission which occurs with when transmitting a single E-DCH stream).
The E-DCH consists of one or more E-DCH Dedicated Physical Data Channels (E-DPDCH) and is accompanied by one E-DCH Dedicated Physical Control Channel (E-DPCCH). The E-DPDCH carries the data traffic and the E-DPCCH carries control information to enable the E-DPDCH to be decoded.
In uplink MIMO, a secondary E-DCH stream is sent together with the primary E-DCH stream. Similar to the primary E-DCH stream, the secondary E-DCH stream consists of one or more secondary E-DPDCH (S-E-DPDCH) and one secondary E-DPCCH (S-E-DPCCH).
Although providing uplink MIMO facilitates transmissions from the user equipment to the network, unexpected consequences can occur.
Accordingly, it is desired to provide an improved technique for supporting MIMO communications.